Climate Control Knocking 2000 TL
 

This winter (New England), an intermittent knocking started that happened when the car was started, would last 10 seconds or so and then stop. As the weather got warmer the knocking frequency increased. Now it is happening whenever the car starts and intermittently while driving. When it happens, I can make it stop by increasing the cabin temperature setting and make it start again by lowering it. I’ve traced it to the climate control system and specificaly to the component in the photo. This is located on the passenger side under the dash, below the left side of the glove box. When I put my hand on It I can feel the knocking inside. What part is this? It doesn’t look like it would be to difficult to replace but I need to know what to order.
Or, is it something else in the system that is the real issue causing this component to knock?
Thanks,
George